As an electrostatic loudspeaker having flexibility and being foldable or bendable, the electrostatic loudspeaker disclosed in Patent Document 1 is available, for example. In this electrostatic loudspeaker, a polyester film on which aluminum is evaporated is held between two pieces of cloth woven with conductive threads, and ester wool is disposed between the film and the cloth.
In addition, the condenser headphone disclosed in Patent Document 2 has a structure in which a vibrating plate is held between fixed electrodes. Electrode foils are formed on both faces of each of the fixed electrodes, and the electrode foil on the front side is not conductive with the electrode foil on the back side. Furthermore, the fixed electrode is provided with a plurality of holes. The electrode foil positioned on the ear side of the user is connected to the ground.